Anth 1 / Waters
IN-CLASS NATURAL SELECTION ESSAY (40 points)
The essay will be written in class on Tuesday, October 28th without the use of notes or the textbook.
You’ll be supplied with the sheets on which to write your essay. Allow yourself plenty of time to prepare
in advance (i.e. study the material pertaining to this topic, practice writing a draft of the essay, etc.). The
purpose of the assignment is to demonstrate your knowledge of natural selection and gain experience
writing a college essay.
The main topic of your essay must be the example of evolution and the sickle-cell allele. You’ll need to
explain why the frequency of the Hbs mutation (the sickle cell allele) is particularly high in western and
central Africa, despite the devastating effects it has on people who are homozygous recessive. Your
essay also must include a discussion of how the key concepts of natural selection such as variation,
selective pressures and fitness apply to this example. Use Chapters Two and Four as your sources
(there’s no need to cite sources).
Your essay must include four-to-five paragraphs (approximately 400-500 words) and be structured using
the format below. Pay careful attention to spelling and proper sentence structure. You must paraphrase,
which means your essay mainly consists of original phrases that are unlike those used by the author of
the textbook or other sources. Using an author’s work word-for-word is considered plagiarism, is against
college policy and will result in a zero on the assignment. Do not use any quotations in your essay.
You’ll be graded on how well you address the required topics outlined below:
INTRODUCTION (1 paragraph)
The main idea of an essay is stated in a thesis statement, which introduces the theme of the essay in one or
two sentences. The thesis statement provides the reader with a general idea of what the essay is going to be
about. Thesis statements are very specific and to the point so the essay stays focused on the subject matter.
An introduction paragraph also includes one or more sentences with examples that provide background
information for the thesis statement. Your thesis statement must include a brief and general description
of the concept natural selection. Back this up with one or more sentences that introduce the main
topic of your essay (i.e. the relationship between natural selection and the sickle cell allele).
SUPPORTING PARAGRAPHS (2-3 paragraphs)
Supporting paragraphs make up the main body of an essay and develop the main idea or topic. In an essay,
the writer develops the main idea by describing facts, details, and examples. Do this by explaining the
facts behind the high frequency of the sickle cell allele in western and central Africa (stick to the main
idea, don’t stray off topic and describe the symptoms of sickle cell anemia in detail). Include a
discussion of the variation in this example, the selective pressures behind the high frequency of the
sickle cell allele, and the individuals with the highest fitness.
CONCLUSION (1 paragraph)
The conclusion comes at the end of your essay, after you’ve finished developing your ideas. It leaves the
reader with a sense that the essay is complete. Include a final/concluding paragraph that “wraps up”
your essay and summarizes several key points you addressed in the supporting paragraphs (this is
not a repeat of what you wrote before, but a summary of the main facts).